CentOS - Apr 2016 - [OT] disk utility showing message "the partition is misaligned by"

greetings.

centos 6.7 [current]


'disk utility' has started showing message;

  WARNING: The partition is misaligned by 2560 bytes. This may
  result in very poor performance. Repartitioning is suggested.

for sdc5 - /home partition.

  /dev/sdc5      302243312 156348604 130534968  55% /home
  /dev/sdc7       80854912     57088  76683952   1% /hdd/c/07

other than time involved to backup sdc5, repartition is not a problem.

to my thinking, but not recalling,  with fsck;

  fsck -rN -t ext4 /dev/sdc5  * to check repairs
  fsck -r -t ext4 /dev/sdc5   * to repair


gparted was used to partition drive. is pmagic live a better choice,
or should i return fdisk because;

=+=+$ sudo fdisk -l /dev/sdc
[sudo] password for geo:

Disk /dev/sdc: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x0009ede7

   Device Boot      Start         End      Blocks   Id  System
/dev/sdc1   *           1         103      819200   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/sdc2             103         230     1024000   82  Linux swap / Solaris
Partition 2 does not end on cylinder boundary.
/dev/sdc3             230        2107    15073280   83  Linux
/dev/sdc4            2107      121602   959844352    5  Extended
/dev/sdc5            2108       42019   320587970+  83  Linux
Partition 5 does not start on physical sector boundary.
=+=+
suggestions for correcting above boundaries also appreciated.

help needed and greatly appreciated.

-- 
peace out.

If Bill Gates got a dime for every time Windows crashes...
 ...oh, wait. He does. THAT explains it!
-+-
in a world with out fences, who needs gates.

CentOS GNU/Linux 6.7

tc,hago.

g
.

Am 22.04.2016 um 12:40 schrieb g <geleem at
bellsouth.net>:
> greetings.
> 
> centos 6.7 [current]
> 
> 
> 'disk utility' has started showing message;
> 
>  WARNING: The partition is misaligned by 2560 bytes. This may
>  result in very poor performance. Repartitioning is suggested.
> 
> for sdc5 - /home partition.
> 
>  /dev/sdc5      302243312 156348604 130534968  55% /home
>  /dev/sdc7       80854912     57088  76683952   1% /hdd/c/07
> 
> other than time involved to backup sdc5, repartition is not a problem.
> 
> to my thinking, but not recalling,  with fsck;
> 
>  fsck -rN -t ext4 /dev/sdc5  * to check repairs
>  fsck -r -t ext4 /dev/sdc5   * to repair
> 
> 
> gparted was used to partition drive. is pmagic live a better choice,
> or should i return fdisk because;
> 
> =+=+> $ sudo fdisk -l /dev/sdc
> [sudo] password for geo:
> 
> Disk /dev/sdc: 1000.2 GB, 1000204886016 bytes
> 255 heads, 63 sectors/track, 121601 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
> Sector size (logical/physical): 512 bytes / 4096 bytes
> I/O size (minimum/optimal): 4096 bytes / 4096 bytes
> Disk identifier: 0x0009ede7
> 
>   Device Boot      Start         End      Blocks   Id  System
> /dev/sdc1   *           1         103      819200   83  Linux
> Partition 1 does not end on cylinder boundary.
> /dev/sdc2             103         230     1024000   82  Linux swap /
Solaris
> Partition 2 does not end on cylinder boundary.
> /dev/sdc3             230        2107    15073280   83  Linux
> /dev/sdc4            2107      121602   959844352    5  Extended
> /dev/sdc5            2108       42019   320587970+  83  Linux
> Partition 5 does not start on physical sector boundary.
> =+=+> 
> suggestions for correcting above boundaries also appreciated.
> 
> help needed and greatly appreciated.


check it with:

blockdev --getalignoff /dev/sd 

(if a '0' is returned, the partition is aligned)

--
LF

Leon Fauster wrote:
> Am 22.04.2016 um 12:40 schrieb g <geleem at bellsouth.net>:
>> centos 6.7 [current]
>> 'disk utility' has started showing message;
>>
>>  WARNING: The partition is misaligned by 2560 bytes. This may
>>  result in very poor performance. Repartitioning is suggested.
>> for sdc5 - /home partition.
>>
>>  /dev/sdc5      302243312 156348604 130534968  55% /home
>>  /dev/sdc7       80854912     57088  76683952   1% /hdd/c/07
<snip>
>> gparted was used to partition drive. is pmagic live a better choice,
>> or should i return fdisk because;
<snip>
1. fsck won't do anything at the lower level of partitioning.
2. A few years ago I personally tested this, and yes, an aligned partition
*does* make a significant difference in access time.
3. I've only used gparted once or twice. In user-surly parted, you want to
run it as
      $ parted -a opt /dev/sdc
    then, when mkpart, be sure to use start and end as something like
x.0GB, +x.0GB,
    and parted will do the alignment correctly. (As opposed to only
telling you
    that the alignment is not optimal, rather than *telling* you what you
should be
    doing to make it optimal.)

        mark

On 04/22/16 08:19, Leon Fauster wrote:
<<>>
> check it with:
>
> blockdev --getalignoff /dev/sd 
> 
> (if a '0' is returned, the partition is aligned)
>
===>

Leon,
thank you for reply.

]$ sudo blockdev --getalignoff /dev/sdc1
0
]$ sudo blockdev --getalignoff /dev/sdc2
0
]$ sudo blockdev --getalignoff /dev/sdc5
2560
]$ sudo blockdev --report /dev/sdc1
RO    RA   SSZ   BSZ   StartSec            Size   Device
rw   256   512  4096       2048       838860800   /dev/sdc1
]$ sudo blockdev --report /dev/sdc2
RO    RA   SSZ   BSZ   StartSec            Size   Device
rw   256   512  4096    1640448      1048576000   /dev/sdc2
]$ sudo blockdev --report /dev/sdc5
RO    RA   SSZ   BSZ   StartSec            Size   Device
rw   256   512  4096   33848955    328282081792   /dev/sdc5

so, blockdev does not show end, but does confirm sdc5 start is off
by 2560, same as fdisk.

all of which indicates i should repartition drive with fdisk.

is there any easier way such as using gparted or sparted so that
partitioning will be by cylinder and not sector?

thank you again. much appreciate.

-- 
peace out.

If Bill Gates got a dime for every time Windows crashes...
 ...oh, wait. He does. THAT explains it!
-+-
in a world with out fences, who needs gates.

CentOS GNU/Linux 6.7

tc,hago.

g
.

On Fri, Apr 22, 2016 at 4:40 AM, g <geleem at bellsouth.net> wrote:
>
> =+=+> $ sudo fdisk -l /dev/sdc
> [sudo] password for geo:
>
> Disk /dev/sdc: 1000.2 GB, 1000204886016 bytes
> 255 heads, 63 sectors/track, 121601 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
> Sector size (logical/physical): 512 bytes / 4096 bytes
> I/O size (minimum/optimal): 4096 bytes / 4096 bytes
> Disk identifier: 0x0009ede7
>
>    Device Boot      Start         End      Blocks   Id  System
> /dev/sdc1   *           1         103      819200   83  Linux
> Partition 1 does not end on cylinder boundary.
> /dev/sdc2             103         230     1024000   82  Linux swap /
Solaris
> Partition 2 does not end on cylinder boundary.
> /dev/sdc3             230        2107    15073280   83  Linux
> /dev/sdc4            2107      121602   959844352    5  Extended
> /dev/sdc5            2108       42019   320587970+  83  Linux
> Partition 5 does not start on physical sector boundary.
> =+=+
What are these units? Tracks? So 1 = 63, so the start of sdc1 is 1=63?
Annoying. I wish these tools would get updated to do sectors by
default, tracks are useless.

You can try

parted /dev/sdc u s p

That should be in sectors. If the start value is divisible by 8, it is
4KiB sector aligned, *assuming* the drive does not have a jumper
enabled for Windows XP compatibility. I'd like to believe those drives
are long gone by now but heck we keep running into ancient versions of
fdisk and parted with bad legacy behaviors.

Use gparted booted from say a Fedora 23 live workstation USB stick
(created with dd), and 'dnf install gparted'. There's an option to
move/resize. Just give it a new start value and keep the size the
same. Moving takes a long time, every sector for the chosen partition
has to be copied and moved forward or backward.

Or back it up, blow it away, and repartition. Any new tool should warn
or flat out prevent you from improperly aligning but the simplest way
to do it is to always align on 1MiB boundaries. For example partition
1 starts at LBA 2048 which is 1MiB aligned, and now make all
partitions sized in MiB increments and they will all align

Depending on the age of the file system, it's not a bad idea to just
start over every once in a while.


-- 
Chris Murphy

On 04/22/16 05:40, g wrote:
<>
> suggestions for correcting above boundaries also appreciated.
>
> help needed and greatly appreciated.
>
===>

thank you all for replies. most helpful. now to decide which way to
format a new drive that i now have on order.

after reading replies, i feel easiest way to get a good partition
layout was a complete repartitioning and formatting.

easiest way to do that is start with a new drive. during install,
i will do partitioning and formatting. that is i am presuming that
installation will know how to properly set up partitions so that
all partitions are by full cylinders.

after new install, transfer my current /home to new drive, wipe
current drive, partition and format it.

anyone see anything wrong with such thinking?


-- 
peace out.

If Bill Gates got a dime for every time Windows crashes...
 ...oh, wait. He does. THAT explains it!
-+-
in a world with out fences, who needs gates.

CentOS GNU/Linux 6.7

tc,hago.

g
.

g wrote:
> after new install, transfer my current /home to new drive, wipe
> current drive, partition and format it.
> 
> anyone see anything wrong with such thinking?
I assume you would have to run grub2-mkconfig and grub2 install
or equivalent.

-- 
Timothy Murphy  
gayleard /at/ eircom.net
School of Mathematics, Trinity College, Dublin

On 04/22/2016 10:18 PM, g wrote:
> after reading replies, i feel easiest way to get a good partition
> layout was a complete repartitioning and formatting.
>
> easiest way to do that is start with a new drive. during install,
> i will do partitioning and formatting. that is i am presuming that
> installation will know how to properly set up partitions so that
> all partitions are by full cylinders.
A new install will default to partitions with 1-Megabyte alignment
(2048 LBA sectors). That is totally unrelated to "cylinders".

-- 
Bob Nichols     "NOSPAM" is really part of my email address.
                 Do NOT delete it.